WO2002096585A1

WO2002096585A1 - Portable drilling machine

Info

Publication number: WO2002096585A1
Application number: PCT/KR2001/001555
Authority: WO
Inventors: No Soo Song
Original assignee: Hosan Technologies Co., Ltd.
Priority date: 2001-05-26
Filing date: 2001-09-18
Publication date: 2002-12-05
Also published as: KR100436754B1; KR20020090252A

Abstract

Disclosed is a portable drilling machine. The machine comprises a drilling cutter; a motor for driving the drilling cutter; a holder for moulding the drilling cutter and the motor; a lift plate erected to be moved upward and downward, with the holder fastered to the lift plate; a casing detachably attached to a workpiece; a side wall formed integrally with and erected at a side of the casing; moving means installed on the lift plate and the side wall to move the lift plate upward and downward; cylindrical members defined with center openings and secured to a surface of the lift plate so that they are spaced apart one from another in horizontal and vertical directions; and guide rods connected to the side wall and extending in the vertical direction, such that the cylindrical members are fitted around the guide rods to be slidingly moved upward and downward thereon.

Description

PORTABLE DRILLING MACHINE

Technical Field

The present invention relates to a portable drilling machine, and more particularly, the present invention relates to a portable drilling machine which has a provision to be firmly attached to a workpiece and is configured to allow a drill to be manually lowered to thereby make a hole in the workpiece.

Background Art

Generally, a portable drilling machine comprises a magnetic body provided at a lower end of the portable drilling machine, a casing having built therein a magnetizing section capable of magnetizing the magnetic body upon application of electric power, a drilling cutter connected to a lower end of a holder positioned at a side of the casing, a motor secured to an upper end of the holder to drive the drilling cutter, a lift plate which is disposed to be moved upward and downward and to which the holder is fastened, a rack affixed to a widthwise middle portion of the lift plate to extend in a vertical direction, a pinion supported by the casing to be meshed with the rack, a handle for rotating the pinion, and a side wall formed integrally with the casing to rotatably support the handle. Therefore, after placing the portable drilling machine on a worktable or a workpiece made of magnetic material, by applying electric power to the magnetizing section, the magnetic body provided at the lower end of the portable drilling machine is magnetized so that the portable drilling machine is firmly attached to the worktable or workpiece. Then, as electric power is applied to the motor, the drilling cutter is rotated. At this time, by turning the handle, the pinion is rotated. If the pinion is rotated in one direction, the rack meshed with the pinion is lowered, and thereby, the lift plate and drilling cutter are also lowered integrally with the rack. By this fact, the drilling cutter can be brought into contact with and make a hole in the workpiece.

Various lift plate guide means have been disclosed in the art, which function to prevent the lift plate from shaking while being moved upward and downward. A typical example of the lift plate guide means is configured in a manner such that the lift plate is coupled to the side wall by a dovetail joint to be capable of being moved upward and downward. However, this type of lift plate guide means suffers from defects in that, since a gap is produced between the lift plate and the side wall, the lift plate is still likely to shake upon upward and downward movement thereof or while performing drilling work. Further, in the case that the portable drilling machine is used for a lengthy period of time, as sliding surface portions of the lift plate and side wall are partially worn out, upon performing drilling work, irregular shaking of the lift plate is caused, and thereby it is difficult to precisely make a hole in the workpiece.

In an effort to cope with these defects, another portable drilling machine has been disclosed in the art, in which a pair of cylindrical members each defined with a center opening are secured adjacent to front and rear portions, respectively, of a surface on the lift plate to extend in the vertical direction. A pair of circular guide rods to be respectively fitted into the cylindrical members are connected to the side wall to also extend in the vertical direction. Hence, the cylindrical members can be moved upward and downward while being fitted around and guided by the guide rods.

Nevertheless, the portable drilling machine constructed in this way encounters a problem in that, since the cylindrical members should be held fitted around the circular guide rods until the lift plate is lifted to an uppermost position, heights of the side wall, guide rods and cylindrical members cannot but be increased, whereby a weight of the entire portable drilling machine and an amount of required material are enlarged. Further, in the case that the portable drilling machine is used for a lengthy period of time, due to wear of the lift plate guide means, a gap is still produced in the lift plate guide means, and thereby drilling precision is deteriorated.

Disclosure of the Invention

Accordingly, the present invention has been made in an effort to solve the problems occurring in the related art, and an object of the present invention is to provide a portable drilling machine which has means for guiding upward and downward movement of a drill in such a way as to improve precision of drilling work.

Another object of the present invention is to provide a portable drilling machine which is reduced in its weight and thereby requires a reduced amount of material, while configured to improve precision of drilling work. Still another object of the present invention is to provide a guide device for drill lifting means, which does not cause shaking of a drill even when the guide device is used for a lengthy period of time.

Yet still another object of the present invention is to decrease the number of maintenance factors for a portable drilling machine and allow maintenance work to be easily performed.

According to one aspect of the present invention, there is provided a portable drilling machine comprising: a drilling cutter; a motor for driving the drilling cutter; a holder for mounting the drilling cutter and the motor; a lift plate erected to be moved upward and downward, with the holder fastened to the lift plate; a casing detachably attached to a workpiece; a side wall formed integrally with and erected at a side of the casing; moving means installed on the lift plate and the side wall to move the lift plate upward and downward; a plurality of cylindrical members defined with vertically extending center openings, respectively, and secured to a surface of the lift plate so that they are spaced apart one from another in horizontal and vertical directions; and at least two guide rods connected to the side wall and extending in the vertical direction, in a manner such that the cylindrical members are fitted around the guide rods to be slidingly moved upward and downward thereon.

According to another aspect of the present invention, each cylindrical member is defined at a side thereof with a cut portion which faces the side wall, and the side wall is formed with at least two projections to be respectively brought into contact with and fastened to the guide rods, in a manner such that the projections can pass through cut portions defined in the cylindrical members when the cylindrical members are moved upward and downward. According to another aspect of the present invention, each cylindrical member is defined, through a wall portion thereof, with a bore which extends in a radial direction to be communicated with the center opening; a ball and a spring are inserted into the bore; and a bolt member for pressing the ball toward the guide rod fitted into the center opening is threadedly coupled into the bore. According to still another aspect of the present invention, a pair of upper cylindrical members and a pair of lower cylindrical members are secured adjacent to front and rear ends on the surface of the lift plate, to be spaced apart from each other in the vertical direction; and two guide rods, around which the cylindrical members are fitted, are connected to the side wall to be spaced apart from each other in the horizontal direction.

According to yet still another aspect of the present invention, the pair of upper cylindrical members are configured to be fitted around the pair of guide rods immediately before the drilling cutter is brought into contact with the workpiece while being moved downward, and the pair of lower cylindrical members are configured to be held fitted around upper end portions of the guide rods when the drilling cutter is lifted to an uppermost position.

Brief Description of the Drawings

The above objects, and other features and advantages of the present invention will become more apparent after a reading of the following detailed description when taken in conjunction with the drawings, in which:

FIG. 1 is a perspective view illustrating a portable drilling machine in accordance with an embodiment of the present invention;

FIG. 2 is a longitudinal cross-sectional view illustrating the portable drilling machine according to the present invention;

FIG. 3 is a perspective view illustrating a part of the portable drilling machine according to the present invention;

FIG. 4 is a transverse cross-sectional view illustrating the portable drilling machine according to the present invention; FIG. 5 is a longitudinal cross-sectional view independently illustrating a cylindrical member of the portable drilling machine according to the present invention; and

FIG. 6 is a perspective view illustrating an operative position of the portable drilling machine according to the present invention, in which a drilling cutter is lowered to make a hole in a workpiece.

Best Mode for Carrying Out the Invention

Reference will now be made in greater detail to a preferred embodiment of the invention, an example of which is illustrated in the accompanying drawings. Wherever possible, the same reference numerals will be used throughout the drawings and the description to refer to the same or like parts.

As shown in FIG. 1, a portable drilling machine in accordance with an embodiment of the present invention comprises a drilling cutter 11 for making a hole in a workpiece, a holder 13 having a lower end to which the drilling cutter 11 is coupled, a motor 12 for rotating the drilling cutter 11 upon application of electric power, a lift plate 21 having one surface to which the holder 13 is fastened by means of conventional fastening means such as bolts (not shown), a support block 22 which is fastened to the other surface of the lift plate 21 to extend in a vertical direction, and a rack 23 affixed to the support block 22.

The portable drilling machine further comprises a magnetic body 40 provided at a lower end of the portable drilling machine, a casing 60 located on the magnetic body 40 and having built therein a magnetizing section (not shown) capable of magnetizing the magnetic body 40 upon application of electric power, a side wall 41 formed integrally with a side of the casing 60, and a handle 50 rotatably installed on the side wall 41. The casing 60 is formed with a handgrip 61.

As shown in FIGs. 1 and 2, a pinion 52 is installed in the side wall 41 to be meshed with the rack 23. Thus, if the handle 50 is turned, a shaft 51 and the pinion 52 are integrally rotated. As the pinion 52 is rotated, the rack 23 can be lifted and lowered, whereby the lift plate 21 having fastened thereto the holder 13, to which the drilling cutter 11 is connected, is moved upward and downward.

The support block 22 and rack 23 are fastened to the lift plate 21 by means of bolts 24. In this regard, it is to be readily understood that the rack 23 can be attached to the support block 22 by welding.

Referring to FIGs. 1, 3 and 4, there is shown means for guiding upward and downward movement of the lift plate 21.

The lift plate guiding means comprises cylindrical members 30 secured to the lift plate 21 and guide rods 43 connected to the side wall 41. In this preferred embodiment of the present invention, four cylindrical members, that is, a pair of upper cylindrical members 30a and a pair of lower cylindrical members 30b are provided in a manner such that they are spaced apart one from another in horizontal and vertical directions of the lift plate 21. The cylindrical members 30 are secured to the lift plate 21 by means of bolts 24. Each cylindrical member 30 is defined with a vertically extending center opening 31. Each cylindrical member 30 is also defined at a side thereof with a cut portion 32 which faces the side wall 41.

Further, each cylindrical member 30 is formed, at another side thereof, with a flattened portion. At the flattened portion, the cylindrical member 30 is brought into contact with and secured to the lift plate 21.

Meanwhile, each guide rod 43 extends in the vertical direction in a manner such that the cylindrical member 30 can be fitted around the guide rod 43 to be slidingly moved upward and downward thereon. In this preferred embodiment of the present invention, a pair of guide rods 43 each comprising a round bar are provided to be spaced apart from each other and locked to the side wall 41 by means of bolts 44.

The side wall 41 is formed, adjacent to front and rear ends thereof, with two projections 41a to be respectively brought into contact with and coupled with the guide rods 43, in a manner such that the projections 41a can pass through the cut portions 32 defined in the cylindrical members 30 when the cylindrical members 30 are moved upward and downward.

As shown in FIG. 5, each cylindrical member 30 is defined, through a wall portion thereof, with a bore 37 which extends in a radial direction to be communicated with the center opening 31. A squeezing member 34 such as a ball and a spring 35 are inserted into the bore 37, and a bolt 36 is threadedly coupled into the bore 37. By screwing the bolt 36 into the bore 37, the squeezing member 34 is biased toward the guide rod 43 by the medium of elastic force of the spring 35.

As a consequence, by screwing the bolt 36 into or out of the bore 37, it is possible to constantly maintain sliding force between the cylindrical member 30 and the guide rod 43. Therefore, in the case that the cylindrical members 30 and the guide rods 43 become worn-out due to use over a lengthy period of time, by screwing the bolt 36 into the bore 37, the cylindrical members 30 can be moved upward and downward without undergoing shake. The cylindrical member 30 is made of the same material as an oilless bearing to smoothly slide on the guide rod 43, and a plurality of carbon rods 33 are embedded in the cylindrical member 30 to minimize frictional force generated between the cylindrical member 30 and the guide rod 43.

As shown in FIG. 6, the pair of upper cylindrical members 30a are configured to be fitted around the pair of guide rods 43 immediately before the drilling cutter 11 is brought into contact with the workpiece (not shown) at a lowermost position of the magnetic body 40 while being moved downward. Hence, when the drilling cutter 11 is lowered while making a hole in the workpiece, all of the upper and lower cylindrical members 30a and 30b are fitted around the guide rods 43 to be slidingly moved thereon. If the drilling cutter 11 is moved upward beyond an upper surface of the workpiece, the upper cylindrical members 30a are disengaged from the guide rods 43, and only the lower cylindrical members 30b are fitted around and guided by the guide rods 43 while being moved upward. As shown in FIG. 1, at the time when the drilling cutter 11 reaches an uppermost position, the lower cylindrical members 30b are positioned at upper ends of the guide rods 43.

Hereafter, operations of the portable drilling machine according to the present invention, constructed as mentioned above, will be described. When it is necessary to make a hole in the workpiece made of magnetic material, by placing the present portable drilling machine on the workpiece and applying electric power to the magnetizing section, as the magnetic body 40 is magnetized, the portable drilling machine is firmly fixed to the workpiece.

Thereafter, if the motor 12 is turned on, the drilling cutter 11 is rotated, and by grasping and turning the handle 50 in one direction with the hand, the pinion 52 is rotated to lower the lift plate 21 and drilling cutter 11.

At this time, the lower cylindrical members 30b are lowered while fitted around the guide rods 43. If the drilling cutter 11 is lowered to reach the upper surface of the workpiece, the upper cylindrical members 30a are also fitted around the guide rods 43.

In this state, by continuously rotating the handle 50 in one direction, the drilling cutter 11 is lowered while defining a hole in the workpiece. At this time, since the upper and lower cylindrical members 30a and 30b are moved downward while fitted around the guide rods 43, the lift plate 21 can be lowered without undergoing shake to precisely form the hole in the workpiece.

Meanwhile, because the guide rods 43 are firmly fastened to the side wall

41 while being brought into contact with the projections 41a formed on the side plate 41 and the projections 41a are fitted into the cut portions 32 of the cylindrical members 30, the cylindrical members 30 can be lifted and lowered unobstructed by the proj ections 41a.

Also, due to the fact that, by screwing the bolt 36 into the bore 37, the squeezing member 34 can be brought into contact with the guide rod 43 with a constant pressure, even when a gap is produced between the cylindrical member 30 and the guide rod 43 during use of the portable drilling machine, the lift plate 21 can be moved upward and downward without undergoing shake.

If drilling work is completed, by turning the handle 50 in a reverse direction, the lift plate 21 and the drilling cutter 11 are lifted. When the drilling cutter 11 is moved upward beyond the upper surface of the workpiece, the upper cylindrical members 30a are disengaged from the guide rods 43, and the lift plate 21 is moved upward while only the lower cylindrical members 30b are guided by the guide rods 43.

Industrial Applicability

As apparent from the above description, the portable drilling machine according to the present invention provides advantages as described below. Due to the fact that a pair of upper cylindrical members and a pair of lower cylindrical members are secured to a lift plate capable of being moved upward and downward integrally with a drilling cutter, to be spaced apart from each other, that a pair of guide rods, around which the upper and lower cylindrical members are fitted to be slidingly guided thereby, are connected to a surface of a side wall, and that the pair of upper cylindrical members are configured to be fitted around and guided by the pair of guide rods from the time when the drilling cutter starts to make a hole in a workpiece, heights of the side wall and the guide rods can be decreased. Also, since the drilling cutter is precisely lifted and lowered in a vertical direction, precision of drilling work is improved. Further, because the pair of guide rods are fastened in a state wherein they are brought into contact with projections formed on the surface of the side wall, and the respective upper and lower cylindrical members are defined with cut portions in which the projections are received, the guide rods are held firmly fastened to the projections. Moreover, by the fact that squeezing members are installed in the cylindrical members to be moved inward and outward in a radial direction by screwing and unscrewing bolts, respectively, the cylindrical members, lift plate and drilling cutter can be moved upward and downward without undergoing shake.

Claims

1. A portable drilling machine comprising: a drilling cutter; a motor for driving the drilling cutter; a holder for mounting the drilling cutter and the motor; a lift plate erected to be moved upward and downward, with the holder fastened to the lift plate; a casing detachably attached to a workpiece; a side wall formed integrally with and erected at a side of the casing; moving means installed on the lift plate and the side wall to move the lift plate upward and downward; a plurality of cylindrical members defined with vertically extending center openings, respectively, and secured to a surface of the lift plate so that they are spaced apart one from another in horizontal and vertical directions; and at least two guide rods connected to the side wall and extending in the vertical direction, in a manner such that the cylindrical members are fitted around the guide rods to be slidingly moved upward and downward thereon.

2. The portable drilling machine as set forth in claim 1, wherein each cylindrical member is defined at a side thereof with a cut portion which faces the side wall, and the side wall is formed with at least two projections to be respectively brought into contact with and fastened to the guide rods, in a manner such that the projections can pass through cut portions defined in the cylindrical members when the cylindrical members are moved upward and downward.

3. The portable drilling machine as set forth in claim 1, wherein each cylindrical member is defined, through a wall portion thereof, with a bore which extends in a radial direction to be communicated with the center opening; a ball and a spring are inserted into the bore; and a bolt member for pressing the ball toward the guide rod fitted into the center opening is threadedly coupled into the bore.

4. The portable drilling machine as set forth in claim 1, wherein a pair of upper cylindrical members and a pair of lower cylindrical members are secured adjacent to front and rear portions of the surface on the lift plate, to be spaced apart from each other in the vertical direction; and two guide rods, around which the cylindrical members are fitted, are connected to the side wall to be spaced apart from each other in the horizontal direction.

5. The portable drilling machine as set forth in claim 1, wherein the pair of upper cylindrical members are configured to be fitted around the pair of guide rods immediately before the drilling cutter is brought into contact with the workpiece while being moved downward, and the pair of lower cylindrical members are configured to be held fitted around upper end portions of the guide rods when the drilling cutter is lifted to an uppermost position.

6. The portable drilling machine as set forth in claim 1, wherein the cylindrical member is made of the same material as an oilless bearing, and a plurality of carbon rods are embedded in the cylindrical member.

7. The portable drilling machine as set forth in claim 1, wherein each cylindrical member is formed, at another side thereof, with a flattened portion and is secured at the flattened portion to the lift plate.